This invention relates to electrical contact elements, connectors and to methods of manufacture.
The invention is more particularly concerned with contact elements of the kind for insertion in a plated-through hole in a printed circuit board. Contact elements of this kind are used in connectors, one-half of which, the backplane comprises an array of contact elements in an insulative housing which sits on the circuit board and provides support and protection for the contact elements. Connection to another circuit board is made by means of the other half of the connector which is separate from the backplane but is arranged to mate with it.
The contact elements of such backplanes are generally made from a single piece of metal, one end of which projects into the hole in the circuit board and the other end of which mates with a cooperating contact element in the other half of the connector. In order to ensure a good mechanical and electrical engagement with the hole, that part of the contact element may be compliant across its width so that it is squeezed on insertion into the hole. Various different configurations of contact element have been devised in order to provide this compliance. In one form, the contact element is formed by machining to a generally cylindrical shape, then flattening a portion of the element out of which is subsequently punched a central slot extending lengthways of the element. That portion of the contact element in which the slot is formed provides a resilient section of the contact element since the opposite sides of the slot are urged resiliently towards one another on insertion in the hole. The manufacture of such a contact element requires several manufacturing steps which have to be performed by different machines, thereby increasing the cost of the contact element. Also, contact by the element with the hole is localized to opposite sides of the element rather than around the entire circumference of the element and the hole.